Drafting instrument



A. G. SANDEN DRAFTING INSTRUMENT April 15, 1930.

Filed March 21, 1929 gwuantoc Alli/Zara. Jana e21 Patented Apr. 15, 1930 UNITED STATES ARTHUR G. SAND'I EN, OF SOUTH BELLINGHAM, WASHINGTON DBAFTING INSTRUMENT Application filed March 21, 1929. Serial No. 348,874.

This invention relates to drafting instruments and has special reference to that type of instrument known as a draftsmans triangle.

.5 It is a matter of common knowledge that the most meager draftsmans equipment includes a 45 triangle, a 60 triangle, a protractor, several irregular curves, and (lividcrs or compasses. If unusual angles are to be drawn either additional special triangles must be provided, or resort must be made to use of the protractor to lay olf these angles. The latter course is uniformly unsatisfactory and consumes much valuable time. Also special triangles are usually provided to aid in expediting section lining.

The primary object of this invention is to combine this multiplicity of individual instruments in a single device that will be easy to handle, easy of interpretation, thoroughly accurate, and inexpensive to manufacture.

These objects are attained in the instrument which is the subject-matter of this invention, which is fully described in the following specification, clearly shown in the accompanying drawing, andaccurately defined in the appended claims.

- The accompanying drawing shows a plan View of my new drafting instrument, which is formed with a flat body of the usual thickness of such instruments, and preferably of transparent material such as clear celluloid,

phenol condensation product, or like material. It will be understood however that it may be made of wood, hard rubber or other non transparentmaterial.

The instrument is formed with the usual base 1, which is considerably shorter than the vertical side 2, and at a right angle thereto.

The third, or hypotenuse, side 3, is formed bythe other curve 10 of a protractor gene rated about the point 4 by the radius 8. This protractor is graduated in the conventional man ner. The other longitudinal side is a right line 11 which if ext-ended would include the vertex 24 of the triangle. This line is disposed at an angle of 15 with respect to the vertical side 2, and 75 with respect to base 1. The upper portion 12 of the side 9 becomes tangent to the protractor curve approximately at the point marked l5, then develops into an irregular curve meeting the side 11 at 13. The bottom portion of opening 7 is bounded by an irregular curve 14 meeting side 9 at 15 and side 11 at 16. V

VVit-hin that portion of the body of. my new instrument described by radius 8 is a large irregular curve opening 17, a small irregular curve opening 18, and a series of circular openings 19, 20, 21 and 22 of varying diameters. Parallel with side 11 is a series of openings 23 which are capable of use either in drawing cross-section lines, or in describing circles, and arcs thereof.

I claim- 1. A drafting'instrument consisting of a body formed with a base, a side at 90 thereto, and a'third side formed by two right lines meeting at an angle of 165, said body having an irregular curve opening therein, one side of said opening being for a major portion of its height, a right line disposed at an angle of 75 with respect to said base, the op posite side of said irregular curve opening being formed for a major portion of its extent by a segment of a circle whose center is the meeting point of said two right lines.

2. A drafting instrument consisting of a body formed with a base, a vertical side at 9 0 thereto, a third side meeting said vertical side at an angle of 45 and said base-at an angle of and subtending an angle of 165,

said body having an opening therein, one

side of which is a right linedisposed at an angle of with respect to said base which if extended would include the vertex of said angle of 45 and whose opposite side is an irregular curve, a major portion of which is the segment of a circle generated about the vertex of the 165 angle.

3. A drafting instrument consisting of a body formed with a base, a side at 90 thereto, a third side formed by two' right lines meeting at an angle of 165, said body having an opening therein the major portion of one side of which is a right line disposed at an angle of 75 with respect to said base, the opposite side of said opening being an irregular curve a major portion of which is the arc of a circle and a tangent thereto, the center-0f said are of a circle being the meeting point of said two right lines.

ARTHUR G. SANDEN. 

